#ifndef __MT_RNG_HPP__
#define __MT_RNG_HPP__



/*
   A class to contain Mersenne-Twister random number generator.
   
   Code based on work by Matkoto Matsumoto and Takuji Nishimura and
   specially the file 'mt19937ar.c'

   Copyright and disclaimer of the original random number generator below,
   followed by OpenMP compatible implementation.

   For usage example refer to mt_rng.cpp
*/



/* 
   A C-program for MT19937, with initialization improved 2002/1/26.
   Coded by Takuji Nishimura and Makoto Matsumoto.

   Before using, initialize the state by using init_genrand(seed)  
   or init_by_array(init_key, key_length).

   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
   All rights reserved.                          

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

     1. Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

     2. Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.

     3. The names of its contributors may not be used to endorse or promote 
        products derived from this software without specific prior written 
        permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


   Any feedback is very welcome.
   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
   email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
*/



#define N 624
#define M 397
#define MATRIX_A 0x9908b0dfUL
#define UPPER_MASK 0x80000000UL
#define LOWER_MASK 0x7fffffffUL



/////////////////////////////////////////////////////
// Class container for MT-RNG based on mt19937ar.c //
/////////////////////////////////////////////////////
class mt_rng{
public:
  // Constructor with default seeding
  mt_rng(unsigned long s = 5489UL);

  // Initialize RNG with a seed
  void Seed(unsigned long s);

  // Initialize RNG with an array
  void init_by_array(unsigned long *init_key, int key_length);

  // Create random number on [0,0xffffffff]-interval
  unsigned long ulrand();

  // Create a random number on [0,0x7fffffff]-interval
  long lrand();

  // Create a random number on [0,1]-real-interval
  double drand_closed();

  // Create a random number on ]0,1[-real-interval
  double drand_open();

  // Create a random number on [0,1[-real-interval
  double drand_open_up();

  // Create a random number on ]0,1]-real-interval
  double drand_open_down();
  
  // Destructor
  ~mt_rng();

private:
  unsigned long mt[N], mti;
};


mt_rng::mt_rng(unsigned long s){
  mti = N + 1;
  Seed(s);
}

// Initialize RNG with a seed
void mt_rng::Seed(unsigned long s){
  mt[0] = s & 0xffffffffUL;
  for(mti = 1; mti < N; mti++){
    mt[mti] = 1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti;
    mt[mti] &= 0xffffffffUL;
  }
}

// Initialize RNG with an array
void mt_rng::init_by_array(unsigned long *init_key, int key_length){
  int i = 1, j = 0, k;
  Seed(19650218UL);
  k = N > key_length ? N : key_length;
  for(; k; k--){
    mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL)) + init_key[j] + j;
    mt[i] &= 0xffffffffUL;
    i++; j++;
    if(i >= N){ 
      mt[0] = mt[N-1];
      i = 1;
    }
    if(j >= key_length) j = 0;
  }
  for(k = N - 1; k; k--){
    mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL)) - i;
    mt[i] &= 0xffffffffUL;
    i++;
    if(i >= N){
      mt[0] = mt[N-1];
      i = 1;
    }
  }
  mt[0] = 0x80000000UL;
}

// Create random number on [0,0xffffffff]-interval
unsigned long mt_rng::ulrand(){
  unsigned long y;
  static unsigned long mag01[2]={ 0x0UL, MATRIX_A };
  if(mti >= N){
    int kk;
    for(kk = 0; kk < N - M; kk++){
      y = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK);
      mt[kk] = mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x1UL];
    }
    for(; kk < N - 1; kk++){
      y = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK);
      mt[kk] = mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
    }
    y = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
    mt[N - 1] = mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1UL];
    
    mti = 0;
  }
  y = mt[mti++];
  y ^= (y >> 11);
  y ^= (y << 7) & 0x9d2c5680UL;
  y ^= (y << 15) & 0xefc60000UL;
  y ^= (y >> 18);
  return(y);
}

// Create a random number on [0,0x7fffffff]-interval
long mt_rng::lrand(){
  return( (long) (ulrand() >> 1) );
}

// Create a random number on [0,1]-real-interval
double mt_rng::drand_closed(){
  return( (double) ulrand() * (1.0/4294967295.0) );
}

// Create a random number on ]0,1[-real-interval
double mt_rng::drand_open(){
  return( ( (double) ulrand() + 0.5 ) * (1.0 / 4294967296.0) );
}

// Create a random number on [0,1[-real-interval
double mt_rng::drand_open_up(){
  return( (double) ulrand() * (1.0 / 4294967296.0) );
}

// Create a random number on ]0,1]-real-interval
double mt_rng::drand_open_down(){
  return( ((double) ulrand() + 1.0) * (1.0/4294967296.0) );
}

mt_rng::~mt_rng(){
}



#undef N
#undef M
#undef MATRIX_A
#undef UPPER_MASK
#undef LOWER_MASK



#endif
